The Experts below are selected from a list of 258 Experts worldwide ranked by ideXlab platform
Frank Abildpedersen - One of the best experts on this subject based on the ideXlab platform.
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tuning methane activation chemistry on alkaline earth metal oxides by doping
Journal of Physical Chemistry C, 2018Co-Authors: Hassan Aljama, Jens K Norskov, Frank AbildpedersenAbstract:We study oxidative coupling of methane (OCM) on alkaline earth metal oxides (AEMOs) doped with either a transition metal (TM) or an alkaline earth metal (AEM) different from that of the host oxide. We assess whether doping can lead to new materials that are better than the pure oxides or deviate from the limitations of the scaling relations. Density functional theory (DFT) calculations show that doped AEMO surfaces follow similar linear scaling relations as observed on pure AEMO; however, doped surfaces bind the adsorbates, hydrogen, and methyl more strongly. Both TM- and AEM-doped AEMOs show that methane activation mostly occurs through a surface-mediated pathway, where at the transition state the methane C–H bond is stretched, and the methyl interacts mostly with the Dopant Atom and the hydrogen with the lattice oxygen. The stronger hydrogen binding in the doped surfaces leads to a lower methane activation barrier; however, in some cases, the catalyst surface binds the hydrogen too strongly, poisoning t...
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tuning methane activation chemistry on alkaline earth metal oxides by doping
The Journal of Physical Chemistry, 2018Co-Authors: Hassan Aljama, Jens K Norskov, Frank AbildpedersenAbstract:We study oxidative coupling of methane (OCM) on alkaline earth metal oxides (AEMOs) doped with either a transition metal (TM) or an alkaline earth metal (AEM) different from that of the host oxide. We assess whether doping can lead to new materials that are better than the pure oxides or deviate from the limitations of the scaling relations. Density functional theory (DFT) calculations show that doped AEMO surfaces follow similar linear scaling relations as observed on pure AEMO; however, doped surfaces bind the adsorbates, hydrogen, and methyl more strongly. Both TM- and AEM-doped AEMOs show that methane activation mostly occurs through a surface-mediated pathway, where at the transition state the methane C–H bond is stretched, and the methyl interacts mostly with the Dopant Atom and the hydrogen with the lattice oxygen. The stronger hydrogen binding in the doped surfaces leads to a lower methane activation barrier; however, in some cases, the catalyst surface binds the hydrogen too strongly, poisoning the active site and making the catalyst inactive. The doped systems are largely constrained by the scaling relations, but sites closer to the optimum of the volcano plot exist, suggesting room for improvement.
A D Andreev - One of the best experts on this subject based on the ideXlab platform.
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room temperature single Dopant Atom quantum dot transistors in silicon formed by field emission scanning probe lithography
Journal of Applied Physics, 2018Co-Authors: Z A K Durrani, Mervyn Jones, Faris Abualnaja, Chen Wang, Marcus Kaestner, Steve Lenk, Claudia Lenk, I W Rangelow, A D AndreevAbstract:Electrical operation of room-temperature (RT) single Dopant Atom quantum dot (QD) transistors, based on phosphorous Atoms isolated within nanoscale SiO2 tunnel barriers, is presented. In contrast to single Dopant transistors in silicon, where the QD potential well is shallow and device operation limited to cryogenic temperature, here, a deep (∼2 eV) potential well allows electron confinement at RT. Our transistors use ∼10 nm size scale Si/SiO2/Si point-contact tunnel junctions, defined by scanning probe lithography and geometric oxidation. “Coulomb diamond” charge stability plots are measured at 290 K, with QD addition energy ∼0.3 eV. Theoretical simulation gives a QD size of similar order to the phosphorous Atom separation ∼2 nm. Extraction of energy states predicts an anharmonic QD potential, fitted using a Morse oscillator-like potential. The results extend single-Atom transistor operation to RT, enable tunneling spectroscopy of impurity Atoms in insulators, and allow the energy landscape for P Atoms in SiO2 to be determined.Electrical operation of room-temperature (RT) single Dopant Atom quantum dot (QD) transistors, based on phosphorous Atoms isolated within nanoscale SiO2 tunnel barriers, is presented. In contrast to single Dopant transistors in silicon, where the QD potential well is shallow and device operation limited to cryogenic temperature, here, a deep (∼2 eV) potential well allows electron confinement at RT. Our transistors use ∼10 nm size scale Si/SiO2/Si point-contact tunnel junctions, defined by scanning probe lithography and geometric oxidation. “Coulomb diamond” charge stability plots are measured at 290 K, with QD addition energy ∼0.3 eV. Theoretical simulation gives a QD size of similar order to the phosphorous Atom separation ∼2 nm. Extraction of energy states predicts an anharmonic QD potential, fitted using a Morse oscillator-like potential. The results extend single-Atom transistor operation to RT, enable ...
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room temperature single Dopant Atom quantum dot transistors in silicon formed by field emission scanning probe lithography
Journal of Applied Physics, 2018Co-Authors: Z A K Durrani, Mervyn Jones, Faris Abualnaja, Chen Wang, Marcus Kaestner, Steve Lenk, Claudia Lenk, I W Rangelow, A D AndreevAbstract:Electrical operation of room-temperature (RT) single Dopant Atom quantum dot (QD) transistors, based on phosphorous Atoms isolated within nanoscale SiO2 tunnel barriers, is presented. In contrast to single Dopant transistors in silicon, where the QD potential well is shallow and device operation limited to cryogenic temperature, here, a deep (∼2 eV) potential well allows electron confinement at RT. Our transistors use ∼10 nm size scale Si/SiO2/Si point-contact tunnel junctions, defined by scanning probe lithography and geometric oxidation. “Coulomb diamond” charge stability plots are measured at 290 K, with QD addition energy ∼0.3 eV. Theoretical simulation gives a QD size of similar order to the phosphorous Atom separation ∼2 nm. Extraction of energy states predicts an anharmonic QD potential, fitted using a Morse oscillator-like potential. The results extend single-Atom transistor operation to RT, enable tunneling spectroscopy of impurity Atoms in insulators, and allow the energy landscape for P Atoms in SiO2 to be determined.
Jens K Norskov - One of the best experts on this subject based on the ideXlab platform.
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tuning methane activation chemistry on alkaline earth metal oxides by doping
Journal of Physical Chemistry C, 2018Co-Authors: Hassan Aljama, Jens K Norskov, Frank AbildpedersenAbstract:We study oxidative coupling of methane (OCM) on alkaline earth metal oxides (AEMOs) doped with either a transition metal (TM) or an alkaline earth metal (AEM) different from that of the host oxide. We assess whether doping can lead to new materials that are better than the pure oxides or deviate from the limitations of the scaling relations. Density functional theory (DFT) calculations show that doped AEMO surfaces follow similar linear scaling relations as observed on pure AEMO; however, doped surfaces bind the adsorbates, hydrogen, and methyl more strongly. Both TM- and AEM-doped AEMOs show that methane activation mostly occurs through a surface-mediated pathway, where at the transition state the methane C–H bond is stretched, and the methyl interacts mostly with the Dopant Atom and the hydrogen with the lattice oxygen. The stronger hydrogen binding in the doped surfaces leads to a lower methane activation barrier; however, in some cases, the catalyst surface binds the hydrogen too strongly, poisoning t...
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tuning methane activation chemistry on alkaline earth metal oxides by doping
The Journal of Physical Chemistry, 2018Co-Authors: Hassan Aljama, Jens K Norskov, Frank AbildpedersenAbstract:We study oxidative coupling of methane (OCM) on alkaline earth metal oxides (AEMOs) doped with either a transition metal (TM) or an alkaline earth metal (AEM) different from that of the host oxide. We assess whether doping can lead to new materials that are better than the pure oxides or deviate from the limitations of the scaling relations. Density functional theory (DFT) calculations show that doped AEMO surfaces follow similar linear scaling relations as observed on pure AEMO; however, doped surfaces bind the adsorbates, hydrogen, and methyl more strongly. Both TM- and AEM-doped AEMOs show that methane activation mostly occurs through a surface-mediated pathway, where at the transition state the methane C–H bond is stretched, and the methyl interacts mostly with the Dopant Atom and the hydrogen with the lattice oxygen. The stronger hydrogen binding in the doped surfaces leads to a lower methane activation barrier; however, in some cases, the catalyst surface binds the hydrogen too strongly, poisoning the active site and making the catalyst inactive. The doped systems are largely constrained by the scaling relations, but sites closer to the optimum of the volcano plot exist, suggesting room for improvement.
Hassan Aljama - One of the best experts on this subject based on the ideXlab platform.
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tuning methane activation chemistry on alkaline earth metal oxides by doping
Journal of Physical Chemistry C, 2018Co-Authors: Hassan Aljama, Jens K Norskov, Frank AbildpedersenAbstract:We study oxidative coupling of methane (OCM) on alkaline earth metal oxides (AEMOs) doped with either a transition metal (TM) or an alkaline earth metal (AEM) different from that of the host oxide. We assess whether doping can lead to new materials that are better than the pure oxides or deviate from the limitations of the scaling relations. Density functional theory (DFT) calculations show that doped AEMO surfaces follow similar linear scaling relations as observed on pure AEMO; however, doped surfaces bind the adsorbates, hydrogen, and methyl more strongly. Both TM- and AEM-doped AEMOs show that methane activation mostly occurs through a surface-mediated pathway, where at the transition state the methane C–H bond is stretched, and the methyl interacts mostly with the Dopant Atom and the hydrogen with the lattice oxygen. The stronger hydrogen binding in the doped surfaces leads to a lower methane activation barrier; however, in some cases, the catalyst surface binds the hydrogen too strongly, poisoning t...
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tuning methane activation chemistry on alkaline earth metal oxides by doping
The Journal of Physical Chemistry, 2018Co-Authors: Hassan Aljama, Jens K Norskov, Frank AbildpedersenAbstract:We study oxidative coupling of methane (OCM) on alkaline earth metal oxides (AEMOs) doped with either a transition metal (TM) or an alkaline earth metal (AEM) different from that of the host oxide. We assess whether doping can lead to new materials that are better than the pure oxides or deviate from the limitations of the scaling relations. Density functional theory (DFT) calculations show that doped AEMO surfaces follow similar linear scaling relations as observed on pure AEMO; however, doped surfaces bind the adsorbates, hydrogen, and methyl more strongly. Both TM- and AEM-doped AEMOs show that methane activation mostly occurs through a surface-mediated pathway, where at the transition state the methane C–H bond is stretched, and the methyl interacts mostly with the Dopant Atom and the hydrogen with the lattice oxygen. The stronger hydrogen binding in the doped surfaces leads to a lower methane activation barrier; however, in some cases, the catalyst surface binds the hydrogen too strongly, poisoning the active site and making the catalyst inactive. The doped systems are largely constrained by the scaling relations, but sites closer to the optimum of the volcano plot exist, suggesting room for improvement.
Z A K Durrani - One of the best experts on this subject based on the ideXlab platform.
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room temperature single Dopant Atom quantum dot transistors in silicon formed by field emission scanning probe lithography
Journal of Applied Physics, 2018Co-Authors: Z A K Durrani, Mervyn Jones, Faris Abualnaja, Chen Wang, Marcus Kaestner, Steve Lenk, Claudia Lenk, I W Rangelow, A D AndreevAbstract:Electrical operation of room-temperature (RT) single Dopant Atom quantum dot (QD) transistors, based on phosphorous Atoms isolated within nanoscale SiO2 tunnel barriers, is presented. In contrast to single Dopant transistors in silicon, where the QD potential well is shallow and device operation limited to cryogenic temperature, here, a deep (∼2 eV) potential well allows electron confinement at RT. Our transistors use ∼10 nm size scale Si/SiO2/Si point-contact tunnel junctions, defined by scanning probe lithography and geometric oxidation. “Coulomb diamond” charge stability plots are measured at 290 K, with QD addition energy ∼0.3 eV. Theoretical simulation gives a QD size of similar order to the phosphorous Atom separation ∼2 nm. Extraction of energy states predicts an anharmonic QD potential, fitted using a Morse oscillator-like potential. The results extend single-Atom transistor operation to RT, enable tunneling spectroscopy of impurity Atoms in insulators, and allow the energy landscape for P Atoms in SiO2 to be determined.Electrical operation of room-temperature (RT) single Dopant Atom quantum dot (QD) transistors, based on phosphorous Atoms isolated within nanoscale SiO2 tunnel barriers, is presented. In contrast to single Dopant transistors in silicon, where the QD potential well is shallow and device operation limited to cryogenic temperature, here, a deep (∼2 eV) potential well allows electron confinement at RT. Our transistors use ∼10 nm size scale Si/SiO2/Si point-contact tunnel junctions, defined by scanning probe lithography and geometric oxidation. “Coulomb diamond” charge stability plots are measured at 290 K, with QD addition energy ∼0.3 eV. Theoretical simulation gives a QD size of similar order to the phosphorous Atom separation ∼2 nm. Extraction of energy states predicts an anharmonic QD potential, fitted using a Morse oscillator-like potential. The results extend single-Atom transistor operation to RT, enable ...
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room temperature single Dopant Atom quantum dot transistors in silicon formed by field emission scanning probe lithography
Journal of Applied Physics, 2018Co-Authors: Z A K Durrani, Mervyn Jones, Faris Abualnaja, Chen Wang, Marcus Kaestner, Steve Lenk, Claudia Lenk, I W Rangelow, A D AndreevAbstract:Electrical operation of room-temperature (RT) single Dopant Atom quantum dot (QD) transistors, based on phosphorous Atoms isolated within nanoscale SiO2 tunnel barriers, is presented. In contrast to single Dopant transistors in silicon, where the QD potential well is shallow and device operation limited to cryogenic temperature, here, a deep (∼2 eV) potential well allows electron confinement at RT. Our transistors use ∼10 nm size scale Si/SiO2/Si point-contact tunnel junctions, defined by scanning probe lithography and geometric oxidation. “Coulomb diamond” charge stability plots are measured at 290 K, with QD addition energy ∼0.3 eV. Theoretical simulation gives a QD size of similar order to the phosphorous Atom separation ∼2 nm. Extraction of energy states predicts an anharmonic QD potential, fitted using a Morse oscillator-like potential. The results extend single-Atom transistor operation to RT, enable tunneling spectroscopy of impurity Atoms in insulators, and allow the energy landscape for P Atoms in SiO2 to be determined.